Migration and admixture history of populations have always been curious and an interesting theme. The West Coast of India harbours a rich diversity, bestowing various ethno-linguistic groups, with many of them having well-documented history of migrations. The Roman Catholic is one such distinct group, whose origin was much debated. While some historians and anthropologists relating them to ancient group of Gaud Saraswat Brahmins, others relating them for being members of the Jews Lost Tribes in the first Century migration to India. Historical records suggests that this community was later forcibly converted to Christianity by the Portuguese in Goa during the Sixteenth Century. Till date, no genetic study was done on this group to infer their origin and genetic affinity. Hence, we analysed 110 Roman Catholics from three different locations of West Coast of India including Goa, Kumta and Mangalore using both uniparental and autosomal markers to understand their genetic history. We found that the Roman Catholics have close affinity with the Indo-European linguistic groups, particularly Brahmins. Additionally, we detected genetic signal of Jews in the linkage disequilibrium-based admixture analysis, which was absent in other Indo–European populations, who are inhabited in the same geographical regions. Haplotype-based analysis suggests that the Roman Catholics consist of South Asian-specific ancestry and showed high drift. Ancestry-specific historical population size estimation points to a possible bottleneck around the time of Goan inquisition (fifteenth century). Analysis of the Roman Catholics data along with ancient DNA data of Neolithic and bronze age revealed that the Roman Catholics fits well in a basic model of ancient ancestral composition, typical of most of the Indo-European caste groups of India. Mitochondrial DNA (mtDNA) analysis suggests that most of the Roman Catholics have aboriginal Indian maternal genetic ancestry; while the Y chromosomal DNA analysis indicates high frequency of R1a lineage, which is predominant in groups with higher ancestral North Indian (ANI) component. Therefore, we conclude that the Roman Catholics of Goa, Kumta and Mangalore regions are the remnants of very early lineages of Brahmin community of India, having Indo-Europeans genetic affinity along with cryptic Jewish admixture, which needs to be explored further.

人口的迁移和混合历史一直是好奇和有趣的主题。印度西海岸拥有丰富的多样性，拥有各种民族语言群体，其中许多人有充分记录的迁徙历史。罗马天主教徒就是这样一个独特的群体，其起源备受争议。虽然一些历史学家和人类学家将他们与古代的高德萨拉斯瓦特婆罗门群体联系起来，但其他人将他们与第一世纪移民到印度的犹太人失落部落的成员联系起来。历史记录表明，这个社区后来在 16 世纪被果阿的葡萄牙人强行改信基督教。到目前为止，还没有对这个群体进行遗传研究来推断他们的起源和遗传亲和力。因此，我们使用单亲和常染色体标记分析了来自印度西海岸三个不同地点（包括果阿、库姆塔和门格洛尔）的 110 名罗马天主教徒，以了解他们的遗传历史。我们发现罗马天主教徒与印欧语言群体，尤其是婆罗门人有着密切的联系。此外，我们在基于连锁不平衡的混合分析中检测到犹太人的遗传信号，而这在居住在同一地理区域的其他印欧人群中是不存在的。基于单倍型的分析表明，罗马天主教徒由南亚特定血统组成，并表现出高漂移。特定祖先的历史人口规模估计表明果阿宗教裁判所（十五世纪）前后可能存在瓶颈。对罗马天主教徒数据以及新石器时代和青铜时代的古代 DNA 数据的分析表明，罗马天主教徒非常适合古代祖先构成的基本模型，这是印度大多数印欧种姓群体的典型特征。线粒体 DNA (mtDNA) 分析表明，大多数罗马天主教徒拥有土著印第安人的母系遗传血统；而 Y 染色体 DNA 分析表明 R1a 谱系的频率很高，这在具有较高祖先北印度 (ANI) 成分的群体中占主导地位。因此，我们得出结论，果阿、库姆塔和门格洛尔地区的罗马天主教徒是印度婆罗门社区非常早期的血统的残余，具有印欧人的遗传亲和力以及神秘的犹太混合体，需要进一步探索。