How old do you got to be to do insemination?
At least 18, unless you have really stupid, uncaring parents.
Then you might have a shot at younger if you could find a stupid,
unethical doctor.
The above, of course, refers to artificial insemination. If you
go about it the old-fashioned way and choose the age of your
partner carefully, there are no legal restrictions. However, the
stupid part still applies if you are under 18.