Whether a dietitian-parents could help you achieve all kinds of goals. Generally you'd be likely to have good health, you're less likely to be obese. Healthy, well-fed people tend to be taller, a dietician could use diet changes to reduce acne problems and whatnot. It is generally accepted that healthy, tall, good-looking people have better chances at achieving all sorts of goals. Also, dieticians are relatively wealthy highly-educated people. A child of a dietician is a child of privilege, upper middle class!

Anyway, my point is exactly that nobody can choose their parents.TimS said:

Any act or process that helps with achieving goals is rational.

I would consider parenthood a process. But having a certain set of parents instead of another has little to do with rationality, despite most parents being 'usefull'. In the same way, I would not consider it rational to like singing, even though the acquired skills of breathing and voice manipulation might help you convey a higher status or help with public speaking. To decide to take singing lessons, if you want to become a public speaker, might be rational. But to simply enjoy singing shouldn't be considered so, even if it does help with your public speaking. Because no rational thought is involved.