Final answer:
Dizygotic (fraternal) twins maintain the same genetic similarity, while monozygotic (identical) twins become less genetically similar after leaving their shared childhood homes.
Step-by-step explanation:
After leaving their shared childhood homes, dizygotic (fraternal) twins maintain the same level of genetic similarity, while monozygotic (identical) twins become less genetically similar.
Monozygotic twins start off as genetically identical because they result from the splitting of a single zygote. However, over time, genetic variations can occur due to mutations and epigenetic changes. On the other hand, dizygotic twins are as genetically similar as regular siblings, sharing about 50% of their genetic material.
Therefore, the correct answer is b) They maintain the same genetic similarity.