Question about evolution, genetic bottlenecks, and inbreeding

Trace everybody back through their mothers, they all lead back to H, not F.

But they are all equally recent. They are all direct ancestors. You agree with that, right?

What is magical or special about Y-adam that makes him the MRCA? The most recent common ancestor is simply the ancestor that is more recently common to the organisms under question. In the diagram shown, T and W are siblings (brother and sister). Therefore, the ancestor that they most recently have in common with each other are their parents. So the MRCAs of T and W are the second couple (from left to right) in the third generation.Who is the most recent common ancestor of S and T? Well, not their parents, however, their fathers are brothers which means the most recent common ancestor is the first couple (from left to right) in the second generation.But wait a minute, their S and T's mothers are sisters too! That means the most recent common ancestor is the third couple (from left to right) in the second generation.In technical terms - it's a bit of a mess.Unfortunately, we rarely have a perfect genealogy like this diagram so we can only go by tracing certain things like the mitochondria. However, this doesn't necessarily get us to the most recent common ancestor, just a common ancestor that is the most recent common matrilineal ancestor. The actual common ancestor is almost certainly going to be more recent than that. So 'Adam' and 'Eve' just give us maximum distances to the most recent common ancestor, but we know it must be closer (in our diagram S and T have more recent ancestors in common with one another even thought their matrilineal common ancestor was from a generation earlier).Edited by Modulous, : No reason given.

In the scenario described, who is the most recent common ancestor of S and T, according to your understanding?