Hilary Duff, Sister Haylie Give Baby Luca Kisses While Swimming: Picture

Kisses for baby Luca! Hilary Duff and her sister, Haylie Duff, took Hilary's adorable son Luca, 11 months, for a swim on Wednesday, March 6.

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The sisters, both wearing swimsuits with their hair pulled up, posed for a picture together in the water. Haylie cradled her nephew and they both showered him with kisses.

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Hilary, 25, posted the cute photo on Twitter and captioned the shot, "Waterbug." Haylie, 28, also tweeted, "Swimming with my Seester and Luca. Favorite way to spend an afternoon."

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Though he's probably still learning how to swim, little Luca has recently learned how to walk.

"Well, I officially have a walking baby on my hands!" Hilary announced on Twitter Feb. 28 of her son with husband Mike Comrie. "It's hilarious . . . the wobble makes it look like he's 3 drinks in!"