No, according to LDS doctrine, being in a household with non-members isn't "living in sin" in any respect. You'd be more likely to be chastised for drinking a Coke, actually (practically no one would do that, though, unless they're really nitpicky about following every single rule).
More often than not, though, "living in sin" can mean things like smoking or drinking alcohol, which is frowned upon a lot more by Mormons than it is by the general population. Things like homosexuality, crossdressing, transsexuality, fetishism and general promiscuity do definitely count as "living in sin", though.