Ethan Hawke believes he's the world's ''best lover.''

The 43-year-old actor was thrilled when his wife Ryan Hawke, with whom he has daughters Clementine, six, and Indiana, four, gave him the title because she is one of the ''smartest people'' he knows.

The 'Boyhood' star told ''My wife says I'm the best lover in the world.

''My mother says I'm really smart.

''My kids say I'm the world's best day.''

He added: ''My wife, my mother, and my kids are the smartest people I know.''

Ethan, who also has daughter Maya, 15, and son, Levon, 12, with ex-wife Uma Thurman, previously admitted he doesn't believe in monogamy even though he has been happily married to Ryan since 2008.

He said: ''My relationship with my present wife is thrilling to me and I'm committed to it. But neither she nor I know what shape the future will come in. Sexual fidelity can't be the whole thing you hang your relationship on. If you really love somebody you want them to grow, but you don't get to define how that happens. They do.''

He added: ''People have such a childish view of monogamy and fidelity. 'He's cheated so he's bad, she's cheated so she's bad,' as opposed to a recognition that our species is not monogamous. To act all indignant, that your world has been rocked because your lover wasn't faithful to you, is a little bit like acting rocked that your hair went grey. Human beings are sexual beings.''