Proven brood-mare

Myles and I were yet again approached by a child-model agent walking to dinner last week. As she and her partner sized him up, she noticed that he bore a resemblance to me. I thanked her. Then she asked if I had any other children.
Suddenly I felt like a proven mare being evaluated. If I had one good-looking child, could I possibly have others?
In livestock terms I am worth something!!
Unfortunately, though, for the agent I had to tell her that he was it, so far.