Mark Twain or Lincoln? Part II

Quote:

If you're not a liberal when you're 25, you have no heart. If you're not a conservative by the time you're 35, you have no brain.

Again, this is attributed to both Twain and Lincoln. A solid source, anyone?

I never heard it attributed to anyone other than Churchill. Or either the Wizard of Oz, one.

For what it's worth, the phrase gets 41 Ghits with lincoln, 12 with twain, but 10,700 with churchill

Now those numbers sound statistically significant.