The chances that offspring would get two identical defective copies of a gene from related parents would be greatly increased.
(offspring; would get; two identical defective copies of a gene from related parents) (The chances that offspring would get two identical defective copies of a gene from related parents; would be increased; greatly)
offspring The chances that offspring would get two identical defective copies of a gene from related parents
would get would be increased
two identical defective copies of a gene from related parents
greatly