How did the Idiom "Tit for Tat "get the current usage? [closed]

tit for tat Etymonline

1550s, possibly an alteration of tip for tap "blow for blow," from tip (v.3) "tap" + tap "touch lightly." Perhaps influenced by tit (n.2)

and the OED

A response in kind to something, esp. an injury or insult, that one has received or suffered; a retaliatory action or sequence of actions; retaliation. In later use also as a parenthetic or interjectional phrase.

As in:

2011 J. C. Hormel & E. Martin Fit to Serve xvi. 217 As we struggled for those last two votes, the tit for tat continued.

Hard to pin any sexual connotatation to tit in this phrase, especially with alterations over time (tip ~ tit - as Etymonline notes. So; How did the Idiom “Tit for Tat ”get the current usage?. It started as tip for tat ... you slap me, I slap you!