Wolf:
Parents, siblings and children have their own issur ervah. What does one have to do with another?
Sam2:
Even if they do grow up together, it doesn’t matter. Once they grow up, it is at least as possible as by any pinuyah that one or both of the cousins will develop a “romantic” attraction to the other.
Who says that R’ Moshe’s halacha doesn’t seem to apply to cousins?