My partner has zero sperm can i choose my second cousin to be the sperm donor?

Legal: And with little genetic risk. It might be better, however, to choose a family member of your partner if you want to put his genetic inheritance into the mix! Some modern techniques can get sperm for in vitro fertilization even from some men with zero sperm so you might want to explore that option, but it is EXPENSIVE and often not possible.

Yes: As long as both of you do not have rare, "recessive gene" illnesses, using a second cousin as a sperm donor is acceptable in terms of genetic risk. These days, genetic counselors can help you determine if you share certain genes which might result in an illness in a baby. I think it's well worth your time to see a genetic counselor before making this very final decision. Good luck!