Characteristics and Examples of Fossil Formation. The many different ways organisms are preserved gives fossils different characteristics. Let's explore a few ways fossils can form. Permineralization is when an organism dies and sediment enters the body, filling in the pores of a leaf, or a bone or a shell.
As you can see, for 2 people with Down syndrome having babies, the chances are as follows: -25% chance their child will be typical (no Down syndrome). -50% chance their baby will have Down syndrome. -25% chance there will be no viable pregnancy.
Finally, in comparison to other birth defects - the ones you asked about - the risk to have a baby with Down syndrome at age 40 is about 1 in 106. The risk of having a child with deafness depends on the family history and the type of deafness. There are many inherited forms of deafness.