Final answer:
Current research emphasizes the importance of both genetic predispositions and environmental factors in understanding heredity and intellectual disabilities, with a focus on polygenetic effects and the range of reaction theory that each person's unique genetic makeup influences their intellectual development.
Step-by-step explanation:
The present research on factors related to heredity and intellectual disabilities is complex and acknowledges that both genetic and environmental factors play a significant role. While it is acknowledged that genetics provide a framework for potential intelligence levels, environmental influences act to either trigger or suppress the manifestation of cognitive abilities. There is an increasing focus on the epigenetic effects where the gene expressions are influenced by environmental exposures and can be heritable, affecting future generations.
Studies in human genetics aim to identify various alleles and examine how they express themselves. Research is increasingly focused on the role of multiple genes, or polygenetic effects, in intellectual disability rather than single gene sites. The concept of range of reaction suggests that individuals respond to environmental stimuli in ways that are uniquely based on their genetic makeup, further indicating that a single fixed measure of potential intelligence is modulated by life experiences and environmental stimulation.
Current research also explores the impact of rich stimulation in early environments on individuals' intelligence levels, while high intelligence seems to have a component of resilience that may help in overcoming environmental obstacles. Overall, the understanding of intellectual disabilities and their link to heredity is guided by both genetic predispositions and the significant role of nurturing environmental conditions.