第1585期:Is DNA testing accurate?

Have you ever wondered why your brother or sister doesn’t look exactly like you despite having the same family tree? If you think that’s odd, even stranger is the idea that you and your sibling may have very different ancestry genes. You have the same parents, and therefore the exact same ancestors, but somehow your DNA tests come back with very different results. How is this even possible?

你有没有想过为什么你的兄弟姐妹虽然有相同的家谱，但看起来并不像你？如果你觉得这很奇怪，更奇怪的是你和你的兄弟姐妹可能有非常不同的祖先基因。你有相同的父母，因此有完全相同的祖先，但不知何故，你的 DNA 测试得出的结果却大不相同。这怎么可能？

Children inherit half of their DNA from each parent, via the sperm from the father and the egg from the mother. Our bodies contain 46 chromosomes, or 23 pairs. However, each reproductive cell has only 23 individual chromosomes. When the bodies of our forbearers created their sex cells, the cells engaged in genetic reshuffling, meaning each of the 23 chromosomes is a unique combination of an original pair. This process is also called genetic recombination.

孩子通过父亲的精子和母亲的卵子从父母双方那里继承一半的 DNA。我们的身体包含 46 条染色体，或 23 对。然而，每个生殖细胞只有 23 条独立的染色体。当我们的祖先的身体创造出它们的性细胞时，这些细胞会进行基因重组，这意味着 23 条染色体中的每一条都是原始一对的独特组合。这个过程也称为基因重组。

This is why Dr. Prosanta Chakrabarty, a scientist who studies fish to help explain the evolution of human beings and our planet, says that your sister could be 10% more 'French' than you, despite having the same primogenitors. And the further you go back in your lineage, the more confusing it can be.

这就是为什么研究鱼类以帮助解释人类和地球进化的科学家 Prosanta Chakrabarty 博士说，尽管有相同的始祖细胞，但你的妹妹可能比你多 10% 的“法国人”。而且你越往前追溯你的血统，它就越混乱。

You inherit 25% of each grandparent's DNA. However, this process of recombination means that inevitably some of their genetic make-up will be lost along the way. This could mean that the genes you inherited from your grandparent, could be completely different to those your cousin received.

你继承了每个祖父母 25% 的 DNA。然而，这种重组过程意味着它们的一些基因组成不可避免地会在此过程中丢失。这可能意味着您从祖父母那里继承的基因可能与您堂兄收到的基因完全不同。

Those studying genealogy should also be aware that modern DNA testing might not give you an accurate idea of your ancestry as it is tested against a current, but incomplete database. Many of the genetic samples come from North America and Western Europe. The genes passed down from your ancestors is sampled and matched with people who originated from a certain area. However, without enough samples from the Middle East or Africa, the results may be inaccurate.

那些研究家谱的人还应该意识到，现代 DNA 测试可能无法让您准确了解您的祖先，因为它是针对当前但不完整的数据库进行测试的。许多基因样本来自北美和西欧。从您的祖先传下来的基因被采样并与来自某个地区的人进行匹配。但是，如果没有来自中东或非洲的足够样本，结果可能不准确。

Dr. Prosanta Chakrabarty says that only 1% of our genetic make-up is unique to us, and that it is an incomplete mash-up of our ancestors'. So, the next time someone says you look a bit like you're from a certain country, you may well be. But it might not show up in your tests.

Prosanta Chakrabarty 博士说，我们的基因构成中只有 1% 是我们独有的，而且它是我们祖先的不完全混搭。所以，下次有人说你看起来有点像来自某个国家时，你很可能是。但它可能不会出现在您的测试中。

词汇表

genes 基因
ancestors 祖先，祖宗
inherit 经遗传而得
sperm 精子
egg 卵子
chromosome 染色体
reproductive cell 生殖细胞
forbearers 祖先
genetic reshuffling 基因重组
genetic recombination 基因重组
primogenitor 祖先，始祖
lineage 血统，家系
genetic makeup 基因组成
genealogy 家谱学
originate 起源于，来自