The overall population is roughly 50:50, but men are more likely to be the "final node" in the family tree.
Let's adjust the example above slightly to include Bob's friend Darren, who who never got laid because he spent his whole life watching pornography and playing video games.
Even in this case, despite the 50:50 ratio of males and females both across society as a whole and within each generation, the child has more male ancestors.
This will be the case for any sufficiently large population where males have more variance in reproductive success than females, and people (of either sex) reproduce with others who have a shared ancestor (the closer the ancestor, the greater the effect the variance has on the ratio of male to female ancestors).
Let's adjust the example above slightly to include Bob's friend Darren, who who never got laid because he spent his whole life watching pornography and playing video games.
Even in this case, despite the 50:50 ratio of males and females both across society as a whole and within each generation, the child has more male ancestors.
This will be the case for any sufficiently large population where males have more variance in reproductive success than females, and people (of either sex) reproduce with others who have a shared ancestor (the closer the ancestor, the greater the effect the variance has on the ratio of male to female ancestors).