The only objective purpose in life is to spread your genes.
Not even that. It's not like you've failed at life if you don't have kids. You just haven't spread your genetic information. Saying that its your purpose to spread them implies it's the genes purpose to be spread. Genes simply are, they don't have a purpose just like you don't; evolution has just given organisms behaviors and mechanisms that make it very likely that they will be regardless of that lack of purpose.