@Craig6 I hear ya 
But on the other hand, when I work with a firearms trainer, I’m essentially putting my life, and the lives of my family, in their hands. If I’m queasy about discussing things like breasts with my trainer, how am I going to get proper instruction? I mean we’re talking life and death here. The Girls are worthy of deference and respect, but they’re not more important than my life, or the lives of my family.
^^^ That. by the way, is a useful tactic in addressing this. When you stack them up against the value of protecting their family… well most women go all mama-bear and get over it.
Personally, if a male firearms instructor says we need to deal with the question of boobs, fine, let’s deal with it.
I mean, is he going to short me on my education because of my cup size? Not teach me something he knows he should teach me because I’m wearing a bra? Are we really NOT going to discuss something that could save my life or the lives of my grandchildren because he might have to say the word “breasts” or because it might make me uncomfortable if he does?
If you’re my teacher, suck it up and teach me.
Now all that said, I am a fan of starting new women students with female teachers because it increases camaraderie and builds on the “if she can, I can” feeling. And there are some conversations that certainly flow more easily and draw on common experiences. I think EVERY woman should have some female teachers along the way. There are differences in what we find comfortable, where our physical strengths are, and how we think and react that its really important for all teachers, male or female, should know.
And… I’ve had exceedingly few opportunities to study with women teachers. So you men need to just get over it and get on with teaching us 
@Craig6 here’s your homework…
practice this, because it’s a pretty useful thing to say as a teacher:
Since we have women in this class, at some point we may have to talk about… breasts. If we do, it will be because how you carry, how you draw, even shooting position may be affected, and what we’re doing here is pretty important stuff. I’m letting you know now so if it comes up, you won’t be surprised.