Feels very wrong that Trump and Obama are of the same generation, but Biden and Obama aren't
Generation cut-offs are rather arbitrary. Biden is a late silent, Trump an early boomer, and Obama a late boomer. Generations themselves are just rough groupings, but obviously Trump and Biden are much closer in age to each other than to Obama despite not falling between the same arbitrary generation lines.
Also, note that some measures of Gen X start at 1960 which would make Obama an Xer, not a boomer. In which case we already have the answer to this question. There’s also the sub-generation “Generation Jones” which straddles the line between Boomer and X. Obama falls there.