It can be challenging to find reputable, unbiased sources on this topic. Here is a collection of some fairly reliable sources on genetically modified organisms and genetic engineering:
What is genetic engineering?
National Geographic has an article that provides information.
The Genetic Literacy Project claims to be scientifically grounded.
Here is more on The Genetic Literacy Project put together by students at Penn State.
Scientific American has an article on this topic, too.
This is information from the Food and Drug Administration.
This is about genetically engineered insulin.
The BBC has a website with information on genetic engineering.
Your Genome explains genetic engineering.
