The risk of birth defects and congenital diseases increases the more closely related the parents are. Deformities, such as polydactylism (many fingers or toes) would be even more common in pairings of siblings than of first cousins, but the risk, while elevated, is not huge and is definitely not a certainty.
Many people have successfully had children with their first cousin. Charles Darwin married his first cousin, who bore him a number of children.
The practice is discouraged in some communities, but not in others.
The children of your first cousins are your children's second cousins.The children of your second cousins are your children's third cousins,And so forth.
The children of your mother's first cousins are your second cousins. The children of your mother's second cousins are your third cousins. And so forth.
The children of your mother's first cousins are your second cousins. The children of your mother's second cousins are your third cousins. And so forth.
If two people are first cousins, their children are second cousins. If two people are fifth cousins, their children are sixth cousins.
The children of your mother's first cousins are your second cousins. The children of your mother's second cousins are your third cousins. The children of your mother's third cousins are your fourth cousins. And so forth.
Your aunt's children are your first cousins and theirchildren are your first cousins, once removed.Your children and the children of your first cousins are second cousins to each other.
The children of your parent's first cousins are your second cousins. The children of your parent's second cousins are your third cousins.
The children of your mother's first cousins are your second cousins. The children of your mother's second cousins are your third cousins.
Your children and your first cousin's children are second cousins.
Your first cousin's children are your first cousins, once removed. They are your children's second cousins. Your second cousin's children are your second cousins, once removed. They are your children's third cousins. And so forth.
All the children of your aunt and uncle are your first cousins. You and your siblings are their first cousins, because you are the children of their aunt or uncle.Your first cousins children are your first cousins, once removed. Your children are first cousins, once removed, to your first cousins.Your children and your first cousin's children are second cousins to each other.
Your child's children are your grandchildren. Your great uncle's children are your parent's first cousins and your first cousins, once removed. Your grandchildren and your great uncle's children are first cousins, three times removed.