Twin Arizona Boys Allegedly Killed By Grandmother

One twin, the 'donor' twin, is small and anemic, the other, the 'recipient' twin, is large and polycythemic. The lives of both twins are endangered by this condition. The meaning of twin is either of two offspring produced in the same pregnancy.

There are different types of twins, identical and fraternal being the most common. Identical, or monozygotic, twins develop from the same fertilized egg that splits into two. These twins are Either of two children born to the same mother on the same occasion: One of two very similar. Learn more. Either of two children or animals brought forth at a birth.