Question

I thought: a parent closeness to a person can be marked as 50%. seems that is 50% of all parts of dna of humans that have variability across all human population. i heard that chimpanzees are 98% close to humans by their dna, so, 100% here may match like absolute 1 or 2 % of dna.

then, if to say only about siblings with both parents same, for simplicity, a sibling also must have 50% closeness in average. then, an uncle has 50% * 50% = 25% . (because he is sibling of a parent). a cousin has 12,5%. (child of uncle). a grandfather is 25%, his sibling is 12,5%, son of his sibling is 6,25%, and grandson is 3,125%, that is, second cousin. third cousin should be 0,78125% .

and here a question appears: so, this number goes very low very quickly, when going to farther relatives. but it should not go to 0, because stranger people also must have some similar genes by chance.

so, i want to ask, what is that average level of the similar genes by chance? what is median level of it? and what is the distance between 2 of the most far persons?

Answer 1

Humans and chimpanzees share about 98% of their DNA, indicating a close evolutionary relationship. The inheritance of DNA among human relatives halves with each subsequent generation, but due to common ancestry and genetic variation, all humans share a considerable amount of genetic material by default, even distant relatives or strangers.

Step-by-step explanation:

The genetic similarity between humans and chimpanzees is approximately 98%, indicating a close evolutionary relationship. When it comes to the inheritance of DNA among human relatives, siblings on average share 50% of their DNA because they receive half from each parent. An uncle or aunt would share about 25%, as they are one generation removed, and this percentage continues to halve with each subsequent generation.

However, due to the fact all humans share a large percentage of their DNA by default, the genetic relatedness doesn't reduce to zero. The genetic overlap that all humans share by chance is a result of common ancestry and the limited variation that mutations have introduced over time. Therefore, even distantly related humans or strangers will still share a considerable amount of genetic material.

The concept of humans sharing genes with organisms such as fruit flies and chimpanzees illustrates not only close relationships within a species or genus but also the complex web of life where distant relations still exhibit genetic overlap. These facts support the understanding that species share common ancestors and have diverged over millions of years through the process of evolution.