Can you combine Bayesian and frequentists probabilities into "a more

[CogitoErgoCogitoSum]

meaningful" probability statistic? For example.

Suppose through logical reasoning you deduce that someone is 70% likely to be female. Can you combine that with the real statistic that 51% of children are born male? Is there a way to combine these numbers into a probability that might be just a tiny bit more realistic or accurate?

Or is this notion completely absurd? If so, why?