Parents can decide how much detail they want to go into the sexual reproductive process but using a book makes this process easier in an otherwise uncomfortable subject. (childdevelopmentinfo.com)
Maybe you remember (or maybe not) learning many years ago that one parent has a set of genes that mixes during reproductive processes with the other parent's genes. (animalkindvet.com)
B. Barnabas, K. Jager, A. Fehér, The effect of drought and heat stress on reproductive processes in cereals. (brc.hu)