I am still trying to figure out what is up with the older cousin . Is she in a relationship with this woman named Yoshino , or is she in love with her own cousin . Is the younger cousin falling in love with her older cousin ? Way too many opening's with this story , hopefully the holes will get filled in as the story progresses .
I think is pretty clear that Ema had a relationship with Yoshino and is using her cousin as sort of replacement. Her cousin on the other hand doesn't know what the hell is happening with her other that she's starting to see girls on a very different light.
I don't think Anna is "starting to see girls in different light." There is no indication of her reaction toward naked bodies of same genders in her past. So all we know is that she could have already been attract to the female population in the first place. But because of Ema recent appearance into her life, not to mention Anna being rather 'charmed' by her 1/6 cousin's beauty, she has became more conscious about the bodies of her female peers, as we see in the locker room of Chapter 2. In short, Anna is not becoming a lesbian, she is becoming aware of her sexuality.
I have also been wondering about the panty sniffing , Could it be a qwerk or maybe a fetish to sniff a virgin's p***y . I don't think it's a sign of dominance , because if she wanted to dominate her little cousin it would be fairly easy . I am curious to see how this story unfolds with Yoshino and Ema with their background story , and maybe we will see the birth of a new lesbian should she choose that route or maybe she will run away from it all and try and find something like the norm .