From the 'floating speech bubbles' scene in #11:

"You understand, don't you, Mac? I've got eight million brothers and sisters, and..."
"It's okay, honey. Really it is. If the Hudson line stops with me what does it matter as long as I have you?"

So it sounds like not having kids was Heather's choice, not Mac's infertility.

- Le Messor
"Is there another word for synonym?"