Sisters' Bond: Love Them, Hate Them

Sept. 9, 2009— -- As with most sisters, there's a lot of squabbling between the three Musco sisters of Garrison, N.Y., Nicole, 19, Daniella, 16, and Alexis, 14. They skirmish over just about everything -- from who gets to sit shotgun in the car, to who cleans up after dinner and who gets to drink the last Pepsi. Often, it centers on who has borrowed stuff from whom.

Nicole was recently packing to go back to college with her two sisters by her side when Alexis asked her about a black sweater that Nicole had borrowed. Nicole told her she wasn't giving it back.

"But that's my black sweater," Alexis said. To which Nicole responded, "I know but I really like it."

When Alexis told her sister that she had some explaining to do, Nicole said, "I don't have to explain. I just figured that eventually you'd get it when you didn't get the black sweater back."

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In the Musco household, like many others, clothing is a major flashpoint for the sisters.

"There's that feeling of being encroached upon," said Deborah Tannen, author of "You Were Always Mom's Favorite! Sisters in Conversation Throughout Their Lives."

"You're always trying to see how close do we want to be? What's too close?" she said. "Well, seeing your clothes on your sister might be too close."

When "20/20" first met the sisters, Alexis found a broken headband she had borrowed from Nicole sandwiched between the sofa cushions.

"I just bought these headbands. You've gotta be kidding me. Everything I give you, you ruin. Every shirt is stained. Every pair of sneakers is crap. Now my headband is friggin broken," Nicole screamed.

Alexis is a target for her two older sisters, who pick on her relentlessly.

"What bugs me about Alexis is the way she wears her makeup, the way she does her hair, the clothes she wears," Nicole said, "Just her whole being annoys me."

But it's all said with a measure of jest. The sisters, part of a boisterous Italian-American clan, also love one another tremendously.

"It hurts at times when they pick on me, but I like the closeness we have. I don't want to picture growing older, not being with them for four years of my life in college," Alexis said.

CLICK HERE to read an excerpt of Tannen's new book.