Question

How twins are formed ?

Answer 1

so first to start with i must say there are two types of twins 1.identical twins 2.fraternal twins 3. conjoined twins  .
identical twins occur when a single fertilised egg splits into two eggs. they are almost alike and share exact genes and have equal sex.
now,  fraternal twin occur when two separate eggs are fertillised by two different sperms. they don't look alike, don't share same genes . they may be a brother and a sister or a brother and a brother or a sister and sister.conjoined twins are born in a very cases . they look alike and are attached to each other


hope it helps . if there are further you may ask me

Answer 2

Identical twins form when a fertilized egg formed by one sperm divides into two halves.Identical twins look exactly same, have same genes and usually of the same sex.Non-identical or fraternal twins form when two eggs are fertilized and both by two separate sperms.Fraternal twins can be of same or opposite sex, don't look exactly like each other and have different genes.And also there are conjoined twins which occur in extremely rare cases.Just like identical twins they look alike, share same genes and are of the same sex but during the spilt ,the embryo doesn't separate fully after fertilization.The developing embryo starts to split into identical twins for the first few weeks and then stop before the process completes.And so two babies are formed but attached to each other. conjoined twins don't survive many days.