Cassandra was overwhelmed by the unknown pleasure of the incestious act that she was doing with her sister and didn't care that their mother was standing there and watching them. She came for the first time and kissed Lisa again while moaning into her mouth. She was still in the afterglow of her orgasm and couldn't hear anything for a few seconds. "Yes...kissing...let's do it again..." Cassy calmed down after taking a few deep breaths and then blushed when she noticed in what situation she was in. "Mom! It's not what it looks like! It's my fault, I asked Lisa to practice kissing with me and then things got out of hand." She knew that what she said didn't make sense and that they got caught red handed in the act. They were both straight and never showed any interest in other girls until now, but the warmth of her naked sisters body felt so good that she didn't want to stop hugging her. Cassy's cheeks were still flushed from the mix of pleasure and embarrassment and her eyes wandered around until they stopped at the sight of her mothers legs, wondering how it would feel to put on pantyhose on herself before she looked at the unbuttoned blouse and then back to her nacked sister while wondering how it had ended like this just from a single kiss.