Comment by bell-cot

Plus, you might want to go back a year pre-conception, at least on the father's side. Sperm cell production is a fairly long process, definitely emphasizing quantity over quality, and thus easy for all sorts of environmental factors to affect - https://en.wikipedia.org/wiki/Spermatogenesis#Duration through https://en.wikipedia.org/wiki/Spermatogenesis#Influencing_fa...