Not from book 1

This is from another entry on twilightsucks.com, but proof that "imprinting" is explicitly sexual. For those who don't know, SMeyer has her werewolves "imprint" - when they see their soulmate, they become obsessed with her.One falls for a girl who rejects him (he's her cousin's fiance), so he brutalizes her and she accepts. One guy falls for the girl who adored him, but who he never gave the time of day. And two imprint on children: a two-year-old and an infant. The ones who fall in love with children become constant fixtures in those little girl's lives, with the expectation of one day having a sexual relationship with them, While SMeyer says, 'Oh, they're just big brothers.... until the girls are old enough!' Imprinting is explicitly sexual because SMeyer is an awful writer. She tells us it's not sexual, but shows very plainly that it is. Proof that imprinting is sexual, even on the babies:

"He'll just have to be patient for a few decades." Eclipse, page 121. Why would he have to be patient if he just wanted to be her big brother? He can be big brother her entire life.

"And then, when she's grown up, they'll be as happy as Emily and Sam." Eclipse, page 121. How can that be if Quil (and everyone else) does not expect a sexual relationship? Jacob says that it isn't romantic, but it obviously is, because he's waiting on her to grow up, so they can be "as happy as Sam and Emily". (Sam is the one who ripped Emily's face off, causing her to realize she loves him)

"But why wouldn't she choose him, in the end?" Eclipse, page 121. Jacob does not understand that obsession is not necessarily reciprocated. Also, no matter how much he states to the contrary, he is expecting this to become a sexual relationship. He is not expecting Quil to simply worship the object of his affections to the end of his days, like he should if imprinting is not sexual. But because it is, Quil is just waiting for Claire to get old enough before telling her that he wants to hit that good.

“Cwaire pway wid Qwil aaaawl day. Cwaire nebber gowin home.” Breaking Dawn, page 97. If that doesn't set off your creep alarm...

"No matter what stage they were in—about to tie the knot like Sam or just a much-abused nanny like Quil—the peace and certainty they always radiated was downright puke-inducing." Breaking Dawn, page 97. Quil is certain that Claire will choose him when he decides to make his move. The idea that she might say no never occurs to him.

"You never saw a real parent so jazzed to play whatever stupid kiddie sport their rugrat could think up." Breaking Dawn, page 98. Because Quil has to be perfect, or Claire won't sleep with him.

"Though I did think it sucked that he had a good fourteen years of monkitude ahead of him until Claire was his age—for Quil, at least, it was a good thing werewolves didn’t get older." Breaking Dawn, page 98. The monkitude. Jacob knows that this is sexual, no matter how much he pretends otherwise. Monks are celibate. Jacob says Quil is going to wait to end his celibacy until Claire's 17 or so.

"He was worse than any paranoid, overprotective mother." Breaking Dawn, page 99. Because no mother is waiting for her child to grow old enough to have sex with.

"His hands flew up to touch Claire, as if making sure she was still there." Breaking Dawn, page 99. CREEEEEEEPY!

"I tugged lightly against his hold on Renesmee, and he just stepped closer to me." Breaking Dawn, page 289. Jacob just can't let go of his sex object.

"Staring at her like… like he was a blind man seeing the sun for the very first time." Breaking Dawn, page 289. But no, that's not sexual, especially not for a grown man looking at an infant.

“You stupid mutt! How could you? My baby!” Breaking Dawn, page 289. Why would Bella be so upset if she didn't know perfectly well it was sexual? If he was just going to be big brother to her little monster, why would she care?

“I can share,” he said pleadingly as he retreated across the lawn." Breaking Dawn, page 290. Generous of him, considering that he's talking to the baby's mother.

"“You think you’ll be part of my family as my son-in-law!”" Breaking Dawn, page 290. Because there's no way he's not going to marry her someday.

"“You’re going to stay away from her,” I hissed up at Jacob.
“I can’t do that!”" Breaking Dawn, page 290. Proof that imprinting is about the imprinter, not the imprintee. He only cares about being around her, not what she or her family wants.

"“He was watching Nessie sleep, his mouth hanging open like the moron he is," Breaking Dawn, page 315. He is sexually fascinated by this infant.

"“I’m not going to think about that for approximately six and a half more years.”
Edward laughed and then sighed. “Of course, it looks like he’ll have some competition to worry about when the time comes.” Breaking Dawn, page 474. Yes, because letting your best friend bang your daughter is so much better at 7 than at 6 months. But still, they're admiring Jacob's restraint in not banging her until she looks grown up.