Twisted,
What is your source that they were not Canaanites. Rashi says that according to R’ Nechemia they were Canaanits. (Beraishis 37:35)
Oomis,
You were taught only one side of a machlokes. The posuk in Beraishis, cited above) refers to Yakov’s “daughters” (plural). R’Yehuda says that each shevet was born with a twin and they married their half-sisters. R’Nechemia says that they married Canaanites and the verse is calling Yakov’s daughter-in-laws “daughters.”