Biologically, human body has 23 pairs of chromosomes (one from the father and one from the mother). On these 23 pairs, there is one pair called sex chromosomes which decides the gender of the person.
In XY - 'X' is from the mother and 'Y' is from the father.
Since women never get Y, the Gotra of the woman is said to be of her husband.
They are different Y chromosomes from the above listed Rishis.
Marriages between same Gotra will increase the risk of causing genetic disorders as same Gotra Y chromosomes cannot have crossover and it will activate the defective cells.
If no Y chromosome is present in this world, then it will cause males to become extinct.