What could be the meaning of "doctor-testing of little girls" by Steinbeck?

Question

I was reading East of Eden by John Steinbeck, where I came across the sentence:

A man’s mind vagued up a little, for how can you remember the feel of pleasure or pain or choking emotion? You can remember only that you had them. An elder man might truly recall through water the delicate doctor-testing of little girls, but such a man forgets, and wants to, the acid emotion eating at the spleen so that a boy had to put his face flat down in the young wild oats and drum his fists against the ground and sob “Christ! Christ!” Such a man might say, and did, “What’s the damned kid lying out there in the grass for? He’ll catch a cold.”

I understand that the overall meaning is that we remember the good and simple things, but not the struggles and pain that were also present.

Still I struggle with the meaning of "the delicate doctor-testing of little girls"; what did the author mean by that?

Answer 1

I suspect that what is being referred to is the euphemism of "playing doctor".

"Playing doctor" is a phrase used colloquially in the Western world to refer to children examining each other's genitals. It originates from children using the pretend roles of doctor and patient as a pretext for such an examination. However, whether or not such role-playing is involved, the phrase is used to refer to any similar examination.

This fits well with the mention of wild oats at a later age, where such experimentation becomes more fraught with emotion and complication.