Passing Down Acquired Traits

An acquired trait is defined as a characteristic or trait that produces a phenotype that is a result of environmental influence. Acquired traits are not coded in the DNA of an individual and therefore most scientists believe they cannot be passed down to offspring during reproduction. In order for a characteristic or trait to be passed down to the next generation, it must be part of the individual's genotype. That is, it's in their DNA.

Darwin, Lamarck and Acquired Traits

Jean-Baptiste Lamarck incorrectly hypothesized that acquired traits could indeed be passed down from parent to offspring and therefore make the offspring more suited to their environment or stronger in some way. ​

Charles Darwin originally adopted this idea in his first publication of his Theory of Evolution through Natural Selection, but later took this out once there was more evidence to show acquired traits were not passed down from generation to generation.

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Examples of Acquired Traits

An example of an acquired trait would be an offspring born to a bodybuilder that had extremely large muscles. Lamarck thought that the offspring would automatically be born with larger muscles like the parent. However, since the larger muscles were an acquired trait through years of training and environmental influences, the large muscles were not passed down to the offspring.

Genetic Traits

Genetics, the study of genes, explains how traits like eye color and some genetic conditions can be passed on from one generation to the next. Parents pass traits to their young through gene transmission. Genes, which are located on chromosomes and consist of DNA, contain specific instructions for protein synthesis.

Some conditions, like hemophilia, are contained in a chromosome and are passed on to offspring. But that's not to say all illnesses will be passed down; for instance, if you develop cavities in your teeth, that's not a condition you'd pass down to your kids.

New Research on Traits and Evolution

Some recent scientific research, however, suggests that Lamarck may not have been entirely wrong. Scientists at the Columbia University Medical Center found that roundworms that developed resistance to a particular virus passed on that immunity to their offspring, and for several generations.

Other research has found that mothers may pass on acquired traits as well. During World War II, the Dutch suffered a devastating famine. Women who gave birth during this period had babies who were more susceptible to metabolic disorders such as obesity. Those children's children were likely to suffer from these conditions as well, research showed.

So while the bulk of the evidence suggests that acquired traits like muscles and obesity aren't genetic, and can't be passed on to offspring, there are some cases where this principle has been disproven.