Question

Select one of the following health problems of middle childhood:obesity, myopia,asthma, or unintentional injuries. Explain how both genetic and environmental factors contribute to it.

Answer 1

• Obesity is simply defined as having too much body fat for your particular weight or height. It is usually measured by an internationally recognised system known as body mass index (BMI). An average figure from research studies estimates that obesity is about 40% genetic and 60% due to environmental factors.
• Environmental factors refer to things like the types of food the child eats, how much food the child eats, amounts of sugary drinks consumed, fruit and vegetable consumption, physical activity level, television viewing, computer use, and the sports children play. The impact of these factors is different for everyone.
• Even lower socio economic status as been linked with obesity in children.Factors such as limited access to resources,poverty, poor knowledge of nutrition and health, increased exposure to fast-food outlets, and limited physical activity due to deprived or unsafe neighborhoods have been suggested to influence energy intake and energy expenditure and, consequently, body weight in children.
• Reduced access to recreational facilities or parks in deprived neighborhoods also may contribute to diminished energy expenditure and thus increased body weight in children of lower SES.
• Parents who restrict their children’s access to foods tend to have heavier children. Restricting children’s access to foods may have the counterproductive effect of making those “forbidden” foods more desirable. also,restriction of foods may teach children to eat in the absence of hunger, that is, to continue eating despite being full when food is available.
• Heritability is the genetic factor found linked to obesity in children.Previous research has shown that obesity runs in families, and twin studies suggest that this is largely due to genetic factors, with heritability estimates over 50%.
• Researchers used a new method called Genome-wide Complex Trait Analysis (GCTA), to investigate the molecular genetic heritability of body weight in children. GCTA takes advantage of the fact that some people are more genetically similar to one another than others, by chance; and looks to see whether individuals who just happen to be more genetically similar might also be more similar in weight. Using this approach, GCTA estimates the combined effects of all known common genes across the whole genome, associated with childhood body weight.
• Using the GCTA method, the researchers found that additive effects of multiple genes across the whole genome accounted for 30% of individual difference in childhood body weight.
• These findings are important because they confirm that in children genes play a very important role in determining body weight. At present only a few genetic variants have been discovered, and these explain a very small amount of individual differences in body weight (around 2%).