Human genes and probability

[Kizzi]

Since there is a limited number of human genes (26 I think),

then what is the probability of 2 babies that are not twins, sharing exactly the same genes?

 

Kizzi:lol:

[MortenS]

Humans have around 30000 genes, distributed on 23 pairs of chromosomes.

 

If we assume no crossing over in meiosis, or mutations, one man can create 2^23 different genetic combinations of gametes

 

A female can also make 2^23 different genetic combination of gametes, again assuming no mutations or crossing over.

 

To find the number of possible offspring from one human couple, multiply these number with each other, and you get 4^23 (or 2^46), which is roughly 7.0 * 10^13 possible combinations.

 

Probabilty of two children sharing exactly the same chromosomes = 1/(7.0 *10^13) * 1/(7.0 * 10^13) = 1/(4.9 * 10^27)

 

Which is a very, very, very small probability

 

There are lots of things not taken into account in this calculation, but you should get the gist. The probability of getting two genetically identical children that are not twins are vanishingly small (for humans, that is)