We only bite the ones we love

As a child I was a biter. Some kids hit, some pull hair, some pinch, I bit. Chomp. I probably bit my sister more than anyone else: she was there more than anyone else.

For the last several years she and I have been going to the same dentist but he only just discovered we are related. When she asked about family resemblances he said:

I didn't think the bites were similar, no, no, Ruth has a bite like noone else on Earth.