Cython does have limited support for generics in the form of its fused types [1]; it can be made to generate C code for different primitive types, for instance. It's nowhere near as flexible as Julia in that regard, since you can't redefine operators for working on Complex numbers for instance, but if you want the interoperability and maturity (read: available programmers and existing libraries) that Python offers, you don't need to trade away generics completely. I'd love to live in a completely-Julia ecosystem, but unfortunately that's not quite reality yet, and luckily Cython is more than capable for making do.

[1] http://docs.cython.org/src/userguide/fusedtypes.html