Even as the memory of the Iranian twin sisters' death remains fresh, two conjoined boys, left by their poor parents after birth, are being looked after at the prestigious All India Institute of Medical Sciences in New Delhi.

The babies, joined at their lower abdomen and born 35 days ago, are normal, healthy and feeding well.

"It is an extremely rare situation, which happens because the embryo starts dividing into identical twins on 13-15 days, but the division is incomplete, leading to two babies joined or united in some regions," Dr D K Gupta, additional professor of paediatric surgery at the institute, said on Sunday.

The twins were born at the Lady Hadinge Medical College and referred to AIIMS six hours after birth. Their parents are from Delhi, are very poor and have abandoned them. They already have two daughters, Gupta said.

The twins have two heads, two upper chests, two hearts, four lungs, but common lower chest, and only two legs. Scanning revealed they have two complete spinal chords.

There are only 20 per cent chances of common feelings for the twins, and that brings the possibility of conflict later in life.

"Thus, if you pinch one leg there are 10-20 per cent chances the twin on the other side would also get hurt," he said. If one cries, there are 20 per chances that other will also cry. They may not be hungry at the same time, but if one is having milk, the sight may also prompt the other to cry for it. Requirements of food may vary."