You can overcome disadvantages (soft limits) with hardwork and care. But IQ/genetics is the hardlimit. You can have rich ass parents and being pampered with tutor and education... but you will be mediocre if your genes are retarded. You can be high iq/gifted but if no opportunity, you will be mediocre as well.

IQ is probably gender bias too. Females are more in middle, while males have more retards and super geniuses that will advance humankind.