Well of course they were good! Tacey wasn't afflicted with that horrible misconception where people tend to think they're better than they actually are. In fact, if anything, Tacey likely under-estimated her ability. Six years of sketching human form; one might hope she was pretty decent at it by now, and the truth was, she was good.
Tacey smiled, nodding and for the most part agreeing. Without thinking that Theo hadn't been well versed in the finer points of genetic inheritance, Tacey started quietly, "Well in Harry's case, it's so much about shutting it out, as simply being dominate, but I think hair color is a polygenic trait...," she trailed looking up at Theo and frowning; the other girl likely didn't care. "I suppose you're right," she nodded, "I mean it's just...for all my vocabulary I can only come up with the word "different". Anyway, red hair was brought to this region by the Norse, so if it evolved better, then it is clearly superior." Tacey again found herself at the awkward end of one of her tangents; she sighed again, deciding it best to just shut up.
"I agree about the brown, I like it. And Rosie and Ri are at either ends of the red spectrum, I think. They're all different too!" Tacey pronounced this, playing Robin to Theo's Batman. "The lot of them are nuts, I think," she said genuinely with a smile, having used "nuts" as an affectionate compliment rather than what Theo would probably take it as. "I can't imagine having such a big family all in school. I don't even have siblings, let alone cousins in Hogwarts!"
Tacey kept her meek expression, not at all convinced by Theo's grin. That girl was sneaky! However, positive talk about her sketch book filled her with life once again. "Well I suppose you'd like to see them before hand, so you can see what you're getting your picture into. I really need to expand my sketch book though, I get so preoccupied with sketching Audrey and Rosie that it's mostly filled with them. Granted they're my roommates, but," Tacey shrugged, having nothing more to say. "It's up in the tower right now, or I'd show you."