Call for Curiosity: What Connects Latvians and Lithuanians in Our Genes?

Have you ever wondered how the genes passed down from our ancestors are reflected in the DNA of modern Lithuanians – and how closely they align with that of our neighbours? According to recent research, Latvians and Lithuanians are not only cultural kin, but also closely related genetically. A study examined genetic links between Lithuanians, Latvians, and Indians and revealed a strong genetic similarity between the two Baltic nations.

According to Dr Alina Urnikytė, Senior Researcher and Associate Professor at the Vilnius University Faculty of Medicine, hunter-gatherer populations inhabited the territories of present-day Lithuania and Latvia until around 5000–4500 BCE, leaving a lasting genetic legacy still visible in both modern populations. 

Latvia and Lithuania: A Deep Genetic Kinship

“Interestingly,” she notes, “northern Samogitians (Žemaičiai) exhibit a unique genetic component also specific to Latvians, while those from the southern highlands of Aukštaitija (Aukštaičiai) carry a genetic component more characteristic of Slavic populations. The Samogitian component likely reflects ancestry from early Baltic tribes such as the Curonians, while Aukštaitian genetics show influence from Sudovians, or Yotvingians.”

This connection forms part of a broader project at Vilnius University (VU), where scientists are uncovering the secrets of the Lithuanian genome. They were the first to sequence genomes of a Lithuanian individual and are now investigating our genetic origins, our links with other populations, and how certain genes help us adapt to environmental conditions.

What defines Lithuanians genetically? According to Dr Urnikytė, Lithuanians are generally characterised by fair hair, light-coloured eyes, and having genes favoured by selection related to fat digestion. In this article, she explains how genetic research is conducted and why the Lithuanian genome is both unique and historically significant.

How DNA Sequencing Works

Over the past few decades, major advances in DNA analysis have allowed scientists to sequence the entire human genome – a complex process requiring both biological and computational expertise. First, DNA must be extracted and prepared, usually from white blood cells taken from a blood sample. These cells contain nuclei, which hold the DNA. Once the DNA is extracted, it is sequenced – meaning that scientists read the order of its four types of nucleotides (A, T, G, and C) that make up the genome’s “text.”

For a sample to be eligible for this kind of research, only individuals who self-reported Lithuanian nationality for themselves, their parents, and grandparents (three generations) are included in the population genomics analysis. This ensures that scientists are studying DNA that reflects the long-term genetic makeup of the local population. To determine changes in the genome over time, researchers must compare DNA across two or three generations.

Dr Urnikytė notes that sequencing a genome once is not enough: “We now use various technologies to sequence either the whole genome or selected parts of it. When sequencing a full genome, it contains about 3.1 billion nucleotides. To ensure quality and accuracy, each base is sequenced at least 35 times.”

A single sequenced genome takes up about 50 GB of storage space. If only specific regions are analysed, scientists typically examine 700,000 to 1.8 million nucleotide positions. The sequencing process itself takes about three days. Once the data is collected, it is uploaded to a supercomputer for analysis – requiring knowledge in both genetics and programming.

What Makes the Lithuanian Genome Unique

So, what makes the Lithuanian genome special? Although humans share ~99.6 % of their genetic material, the remaining difference represents huge diversity – including differences in appearance, physiology, and disease susceptibility. “Even that ~0,4% is significant,” says Dr Urnikytė. “It still adds up to millions of nucleotide differences, which determine our individual traits. While the genome doesn’t define a nation in a strict sense, it can reveal patterns that result from historical adaptation and natural selection.”

Lithuanians carry a unique genetic blend shaped by millennia of migration and survival. Genetic markers trace back to Western hunter-gatherers, Indo-Europeans, and Late Neolithic/Bronze Age peoples. Despite centuries of disease and foreign invasions, a distinct genetic profile has persisted. VU researchers have identified genes shaped by natural selection that influence traits such as fair skin, hair, and eye colour. These features vary within the population but are especially prevalent.

The geneticist also explains that genes determine not only the fair complexion, hair, and eyes of Lithuanians but also other physiological traits: “Some genes, shaped by ancient rather than modern natural selection, were influenced by local pathogens and are linked to more efficient fat metabolism. However, we have not yet been able to identify their exact function. My hypothesis is that these genes were inherited from hunter-gatherer ancestors who needed them not only to break down fats, as they consumed a lot of fish and meat but also to maintain energy levels in a cold climate. Since this is just a guess, we plan to continue researching these genes.”

Adaptation to Climate and Diet

The origins of Lithuanian appearance, particularly fair hair and blue or greyish eyes, also relate to geographic and climatic adaptation. After the Ice Age, early settlers had to adapt to environments with low sunlight. Initially, hunter-gatherers in the region had darker skin and hair but blue eyes. Over generations, their skin lightened to improve vitamin D absorption – vital for bone health and especially for women’s reproductive health, as it influences pelvic structure.

“If the body cannot absorb enough vitamin D, the pelvic bones soften, making childbirth more difficult and threatening population survival,” explains Dr Urnikytė. “This pressure to survive resulted in a higher prevalence of lighter skin, and eventually, the dominant traits became the ones we now associate with Lithuanians.”

She also notes that the Indo-Europeans, who arrived later, brought agriculture and animal husbandry to the region. One important legacy of this shift is the ability to digest milk. Humans are not naturally lactose-tolerant beyond infancy, but genetic mutations enabled some populations to continue producing lactase – the enzyme that breaks down lactose – into adulthood. “This mutation occurred quickly in evolutionary terms, over just a few thousand years. Still, not everyone has it today, which is why some people remain lactose intolerant,” adds the researcher.

Toward Personalised Health and Medicine

Genetic research may also hold the key to a healthier future. Dr Urnikytė points out that an individual’s genome can offer clues about their susceptibility to various diseases or reactions to medications. As we gather more data about Lithuanian (and Baltic) genetic features, this information can be used to identify people at risk for conditions such as cardiovascular diseases, cancer, or diabetes – and allow for early intervention.

One promising field is pharmacogenomics, which explores how genes influence the body’s response to medicine. “Lithuanians may carry certain genes that affect how medications work in their bodies. This information can help doctors choose safer, more effective treatments with fewer side effects,” says Dr Urnikytė.

In the future, genome research may also lead to personalised nutrition, tailoring diets based on an individual’s ability to metabolise certain nutrients. “We already know of genes linked to fat metabolism shaped by natural selection. Next, we plan to collaborate with cardiologists and life scientists to explore how these genes affect heart disease and dietary needs,” she concludes.