This week's cover of Time magazine shows a mother nursing her 3-year-old son.

The California mom at the center of the Time magazine cover controversy knew there would be backlash, but she posed for photographs while nursing her 3-year-old son anyway.

"Out of all families, I really feel like somebody has … to start the dialogue and I feel like our family is confident enough to be the ones to do it," Jamie Lynne Grumet, 26, told "Nightline" correspondent Juju Chang.

PHOTOS: See more controversial magazine covers here.

If Grumet was looking to start a dialogue, she succeeded. The image of the thin, blonde Grumet and her son, who stood on a chair to reach her left breast, went viral and attracted both admiration and derision, with critics questioning whether Time's photo was overly sexualized and, more broadly, whether Grumet and moms like her were harming their children through what's known as extended breast-feeding - nursing a child after he or she is 1 year old.

Watch the full story on "Nightline" tonight at 11:35 p.m. ET.

Whether there are, indeed, consequences to extended breast-feeding seems to be anyone's guess.

"We don't have the long-term data," women's health expert Dr. Jennifer Ashton told "Good Morning America." "We have to follow [Grumet's son] and lots of them until they're 40 and find out: Did they win a Nobel prize, are they a serial killer or are they normal?  But I think it's important to always remember that most moms, they're not trying to hurt their kids, they're trying to do what's best for their children. I don't think this is like putting a cigarette in your child's hands."

ABC News' chief health and medical editor, Dr. Richard Besser, said it used to be typical in hunter-gatherer societies for children as old as 5 or 6 to be breast-fed.

Today, he added, "When I see a child who is doing extended breast-feeding, I really look hard at how they are developing. … If a child is making friends, is developing, is interacting normally, is learning to eat other foods in a normal way and is still occasionally nursing, that's not a big deal."

But Besser said he has seen cases where breast-feeding by older children indicated a problem.

"It's been a big clue into a dysfunctional family relationship," he said. "It's not always the case, but you want to look and see what's going on in that family."

Grumet, herself, was breast-fed until she was 6 years old and acknowledged, "I was on the older age of that spectrum of what's considered normal human weaning," but added, "My mom let me do what was right for me."

Grumet believes she's doing what' s right for her children - she also occasionally breast feeds her adopted 5-year-old son, she told Time - despite the heavy criticism she's weathered. Some have accused her of molestation.

"I think it's a lot of ignorance and so it's really hard to get mad at that," she said. "It's almost an ethnocentric, western perspective on how we see breast in our culture, and it's definitely not a global view. … It's really, really hard for people to understand that breasts are mammary glands and this is what they were designed for, and there's nothing [any more] sexual than any other part of the body."

She is a proponent of attachment parenting - the parenting philosophy explored by Time in its cover story - the tenets of which include extended breastfeeding, baby "wearing" through slings and co-sleeping. Grumet also home-schools her children.

"I want my children to have what my parents gave me and that's kind of a global perspective; be able to travel with them, show them other cultures, and so they understand why we did this … [to] really to teach them to stick up for what's right even if it's hard."

Grumet said one thing she doesn't want to do is pit mothers against one other over the practice of attachment parenting. A number of critics, including mom bloggers, have argued that Time's cover - with the headline "Are You Mom Enough?" - unnecessarily fanned the flames of the proverbial mommy wars. (See more at our sister site, Babble.)

"If it's not working for you, then don't feel guilty," she said. "You just do what's right for your family, and your child is not going to suffer if the family is happy."

Time magazine staff writer Kate Pickert defended the cover, which hit newsstands today.

"I think to say this is part of the mommy wars is a bit of an oversimplification. I think the cover line that we have - 'Are you mom enough?' - is provocative, but I think it's a question, you know, every parent asks themselves: how they're doing in terms of parenting their child," she said. "It sort of gets to a debate that kind of exists within every parent.

"I think that we knew it would be a provocative cover but we're thrilled that lots of people are responding to it," Pickert said. "We're happy to see that we've sparked a great conversation."

ABC News' Katie Kindelan contributed to this report.