Do you think that ethical questions can be answered by science?

Answered by science? Probably not.
But ethical debates can be informed by science.

For example, people used to think that being gay was immoral, because it was assumed that people made a choice to be gay. Brain science has shown otherwise, and attitudes have been changing. While science does not give the definitive answer to how society is to regard gay people, it does affect the direction of the discussion.

No. Philosophy is closer.
(True*) values are built on world view, your beliefs about what reality is.

*True meaning I'm excluding people who make it up as they go, because it's usually not well thought-through and inconsistent. 'True' value systems can differ significantly though - as long as they are consistent with the presuppositional values.

Interesting question. Assuming bad values are negative and good are positive in value, just how would assignment of social values be arrived? And what weight should any value be given?

See the problem? See also Isaac Asimov and the positronic brain. Sure it's sci-fi, yet there was some interesting questions proposed in those series of books.

Note Isaac Asimov was both a scientist and
mathematician himself.

http://www.asimovonline.com/oldsite/Essays/mathematics.html

I think Scientists need to have Ethics....

I don't think that is what science is for.

Sometimes, but until science grasps the basic message of Jurassic Park (just because you can doesn't mean you should); I don't trust the bastards.

No, science cannot prove ethics as ethics are strictly sociological.

[c=#359E00]no, science lack ethic. This is why i avoid scientist[/c]

100% by nature but there are two sides to every leaf...

i don't think so since science deals in facts

show an example?