Final answer:
The mental similarities between adoptive children and their adoptive parents vary depending on both genetic and environmental factors, with environmental exposure potentially increasing similarities to some extent, but genetics providing a boundary to these similarities.
Step-by-step explanation:
The question pertains to the mental similarities between adoptive children and their adoptive parents as they age. Given the information provided, we can deduce that mental similarities do not necessarily increase over time. This is because the mental development of children is influenced by a combination of genetic and environmental factors. While adoptive children may adopt some behavioral and cognitive traits from their adoptive parents due to shared environmental influences, underlying genetic factors play a crucial role in their mental development. Hence, the correct answer should reflect that these similarities vary depending on both genetic and environmental factors. Adoptive children may show some increase in similarities due to environmental exposure but ultimately, genetic factors set a boundary to the extent of these similarities.
For instance, studies indicate that there is a relationship between genetic predispositions and the development of mental health conditions like schizophrenia, with a higher likelihood of development in individuals with high genetic risk versus those with low genetic risk. This is modified by the environment, as indicated by the lower rates of schizophrenia in high-risk adoptees raised in healthy environments compared to disturbed environments.