British lawmakers will vote Tuesday on whether to allow scientists to use controversial techniques to create babies from the DNA of three people, a move that could make the country the first in the world to allow embryos to be genetically modified.

The techniques are intended to prevent children from inheriting potentially fatal diseases from their mothers, and involve altering a human egg or embryo before transferring it into the mother. British law currently forbids any modification of embryos before they are transferred into a woman.

Critics insist the techniques cross a fundamental scientific boundary, since changes made to the embryos will be passed on to future generations, and say approving these techniques could lead to the creation of "designer babies."