Expert: Barbara Silber - 4/13/2005

Question
Hi!

I have noticed an interesting trend when chatting with people about genetics in that they have inherited certain traits that their parents were not born with but somehow seem to have passed down. For example, my brother has never been able to fully twist his right arm so that his palm is facing up - my grandfather (who my brother resembles most) is also unable to do that due to an arm wrestling match he had as a teenager - Another example - my uncle has a big nose ONLY because he's broken it SO many times, his daughter, who resembles him the most has the exact same size and shape of nose as her father. Example #3 – I have a friend who has a mark on the inside of his arm (his sister has this too) and it matches the exact same mark that their father has  that he got from a knife wound.- these are some of MANY (of what I find to be) interesting situations that I know of, which leads me to my question - can our genes/DNA be enhanced or manipulated based on things that happen in our lives and then be passed down to our children as the new genes that they've become? If so, this can lead to many more interesting questions – such as effects of medications, plastic surgery, emotional trauma, etc. and how these things would affect offspring. I would imagine that the sensible answer to my question would be “yes” especially when we look at breeding animals for example. If a certain breed of dog was originally (and I'm talking ancestors here) bred to be a watchdog, or a herding dog, these were things that were TAUGHT  - the offspring suddenly have a natural tendency to guard or herd without being taught to do so…hmmmm?



Please let me know if you have an answer(s) to this plaguing question in my mind.





Thank you,


Answer
Dear Kelly,

The inheritance of acquired characteristics, Lamarck's hypothesis, has not been shown to be true. Using your example of dog breeding, the animals that were able to learn a behavior were bred. The selection is for ability to learn a task not to be able to do it without training.

Remember, if you cut off the tail of a certain kind of dog for many generations the next generation of dogs will still have tails.

I hope that this helps you. The examples you quote are coincidence not inheritance of acquired traits.


Barbara Silber