I am not a teacher.
'To take to' is to fall into the habit of doing something.
There had been a conversation between the speaker/writer and Tish, and this was possibly a cause for embarrassment or feeling of discomfort. Whenever the writer thought about it, he/she tried not to think of it as the 'sex conversation'.
It's slightly convoluted, (intentionally so, I would guess) for humorous effect.
Student or Learner