If you look at many top professional performers, it usually seems like the younger siblings are better. Haven't read the article yet, but my theory would be tha

If you look at many top professional performers, it usually seems like the younger siblings are better. Haven't read the article yet, but my theory would be that the younger brother gets to practice against his sibling that's a year or two older. My guess would be that this would be particular to sports where 1v1 is a priority like tennis or basketball.