According to Eliezer Yudkowsky's research on how to design a General AI which will not go sky-net and kill us with nukes (or worse,) it is.
His hypothesis goes that the human brain is the most complicated thing in the known universe, and that humans have hundreds or thousands of disconnected desires. One example he gives is surgery: You shouldn't stab people with knives; unless you are a surgeon; but then only if you have a filled-out consent-form, otherwise it is malpractise.
The thesis then goes, that brain damage, neurological disorders and psychological disorders can turn people callous and strange, so ethics on an individual basis is most definitely a thing of the human mind.
Further he argues that if ethics were external to humankind, why should we follow it. He has an article wherein he poses the hypothetical scenario where the Stone Tablet of Morality (tm) commands thee to do despicable or weird things. In that case, Yudkowsky would elect to disregard the Tablet and not do despicable.
Yudkowsky makes a point of playing malvolent wish-granting genie with people who come to him with ethical theories not rooted in the human mind; going so far as to write fictional portrayals of "wishes gone wrong," to quite horrific extent in his story Failed Utopia #4-2 wherein a researcher has activated a superintelligent AI, which changes the world order in ways which are only almost right.
ETA: Yudokowsky does at no point argue that ethics are subjective, based on them not feeling that way, nor working out that way in thought-experiments involving altered states of mind, with reasoning as follows: Even if you get lobotomized to think murder is the right thing to do, it is still the wrong thing to do.