Answer:
Through meiosis
Please find the description below
Step-by-step explanation:
Humans reproduce via a type of reproduction called SEXUAL REPRODUCTION. Sexual reproduction is the type of reproduction that involves two sexes (male and female) of an organism. The males produces male gametes called SPERM while females produce female gametes called EGG.
The process by which these gametes is produced is called MEIOSIS. Meiosis is a division that reduces the chromosome number of the parent cells. According to Gregor Mendel, it occurs in such a way only one allele of a gene is present in each gamete.
Hence, according to this question, getting one copy of a sickle cell gene and one copy of a normal gene is as a result of meiotic division of male and female. One parent undergoes meiosis and contributes the normal allele (S) while the other parent undergoes meiosis and contribute the sickle allele (s).