A bit ironic, really - Father being mum.

However, on a more serious note, my grammar check (for what little it is worth ) accepts the sentence with or without a comma.
Personally, I prefer it without but I think it might depend a little upon exactly what the beginnig of the sentence said, and how long it took to say.
(i.e., is there a difference, from this point of view, between a simple and a complex sentence?)