American supermodel Kate Upton feels she is her biggest critic when it comes to motherhood and feels there is always something that she lacks as far as parenting is concerned.

Talking about the challenges of being a parent, the Sports Illustrated swimsuit model, who has a daughter Genevieve, one, with baseball star Justin Verlander, told People magazine: "My biggest mom shamer is myself. We're always trying to be the best we possibly can and that's why I like to speak out about the subject. Because we're all trying to do our best and be our best, and we need to support each other in those efforts.