I've not typically found that to be true. My Black Stars (Black Sex Links) have nearly always been friendly. With my Red Stars (Red Sex Links), it has varied a lot more (many of them have been quite standoffish and occasionally some are aggressive. I think part of the problem is that hatcheries use so many different breeds of silver gene hens to breed their Red Sex Links (Rhode Island Whites, White Rocks, Silver Laced Wyandottes, Delawares, Light Sussex, etc.) that you get a lot more temperament variation in the Red Sex Links than in the Black Sex Links which are almost universally bred by hatcheries using Barred Rock hens.Black Stars and Red Stars have the same temperament.