Filing is done by the applicant, who is generally the employer of the inventor (i.e. the company they work for). Each inventor must have made a significant innovative technical contribution to the invention, and anyone who makes such a contribution has to be an inventor. Managing or employing an inventor doesn't count. The only bias I can think of is that the patent might be filed some time after the invention was made, but in my experience this is at most a few years, usually one or two. Source: I am an inventor on six patents (average age 40).
Vox had an article on something related to this [0], but you'd have to take an extra step to say this means these the inventors, at 20-years-old, were or weren't obtaining patents because of parent income.