I’ve been corrected by fellow blogger, Rabbi Jason Miller.
Turns out Ben Stiller was falsely playing the patrilineal card on “Saturday Night Live”: according to Wikipedia at least (sorry, I don’t have any connections with the Stiller family, so I can’t confirm at this moment) his mother, Anne Meara, converted to Judaism before he was born.
So the Torah does accept him as 100 percent Tribesman. At least those interpreters of Torah who accept the validity of Reform conversions. Which is a slightly larger circle on the Venn Diagram of Jews than the circle of those who accept the validity of patrilineal descent.
Perhaps Stiller was thinking more of his own two children, as their mother/his wife, Christine Taylor, is presumably not Jewish. (Unless there was a conversion that Wikipedia hasn’t told us about.)
Ben, your whole family is welcome at my Reform temple in Forest Hills, Queens, anytime you want. We’ll even give you an aliyah. Just don’t kvetch about the food like you did on that "Jewish Food Hallucination" SNL segment with Andy Samberg.