Now 18, Ponchalearm's changes are all the more striking as he sits, slim and ladylike in a top of white satin and black lace, next to his stern and athletic twin brother.
Ponchalearm's aunt absent-mindedly runs her fingers through his waist-length auburn hair extensions as the family quietly discusses whether Ponchalearm is ready for a sex change operation.
"It's my life and I've decided that I must do it before university," Ponchalearm says. "I feel happy, it's fun, I can express myself as I want. I'm lucky I have friends who understand me."
As he speaks, his mother softly cuts in to express her concern that he is too young to understand the long-term consequences of his decision.
"Let's consider this, you're still too young," she says. "I want him to take time to grow up a bit."
For two years Ponchalearm has yearned for the operation and at 18 he has reached the age at which, under a new Thai health regulation, he can legally make the decision himself.
The regulation was introduced in April after health authorities became alarmed by stories and the subsequent public debate about underage boys seeking -- and receiving -- castrations as the first step toward gender reassignment surgery.
Some gay activists and parents worried about potential side effects of the operation on bodies that are still growing believe the age at which youths can independently make the decision to be castrated should be raised to 20.
"They're trying to do everything to make themselves look like a real woman," said Nathee Teerarojanapong, head of the Gay Political Group of Thailand.
"Why can't they forget about the external beauty and look inside?"
Thailand is believed to have one of the largest transgender populations in the world. Academics estimate at least 10,000 live in Thailand, though other guesses are more than 10 times higher.
Surgery to remove the testicles apparently carries very little inherent physical risk but the side effects of the hormone drugs that must be taken to hasten the transformation from male to female can include hot flushes, weight gain, muscle loss and a loss of libido, as well as tiredness.
Aside from the psychological impact of that such profound change can bring, some doctors who are expert in gender reassignment insist that any fears of physical side effects are exaggerated.
"There are no serious side effects," said Thep Vechavisit, a leading Thai sex change doctor. "People are stupid and talk about things they know nothing about. These activists are hurting transgender people."
Current precautions, which require men to consider their decision for one year and see a psychologist for assessment of their suitability and mental readiness for the operation, are sufficient for weeding out the half-hearted, he said.
"Usually these kinds of people are very young when they're willing to become a woman," Thep said.
"They show up and they've made their decision already. In 20 years I have only had one patient come in and say, 'Doctor, I want my penis back'."
But some people who have already had the operation say the controversy has made them nervous.
Chatpakorn "Belle" Chotiem, a cabaret dancer in Pattaya, said he was castrated five years ago aged 14, after one of his friends had the operation.
"She was so beautiful, a beautiful girl, and I hoped to be like her so much," Belle said. "Now I don't know what to do. I'm so worried about what will happen later."
Ponchalearm's mother said she doesn't want her son in the same situation.
She said she first heard rumours about side effects from a doctor talking about the castration ban on a talk show.
Until then she had been willing to accept her son's decision, Valee said, but now she is not so sure.
"I don't want him to get the operation because I'm afraid he'll get hurt."
If her son won't reconsider, Valee said she was willing to pay for the operation so he could have it at a respectable hospital rather than an underground clinic.
"Whatever he becomes, he's my child," she said.
Although he says he always wanted to be a girl, Ponchalearm only began thinking seriously about the operation after starting at a new high school where he met about 50 other "ladyboys" and felt that for the first time in his life he was among people who understood him.
None of his trendy, soft-speaking, cross-dressing friends have yet gone through with sex change surgery, he said, but some are on the one-year waiting list.
He admits the long wait for the surgery -- and the thought of the blood that goes with it -- have made him squeamish.
"I try to convince myself that I need to do this," he said. "I must."
But his mother fears it's a passing phase and see no easy solution.
"My real wish," she said, "I wish my son was like normal people. Since he was born male, he should be male."