Goodness, what a big question! I'll try for an answer - it won't be the answer, of course, because we aren't all clones of one another who share exactly the same views on the definitions of "morality" and "ethics". Cover me, Tex, I'm goin' in.....
I'd say that children learn ethics and morals from the same places we and all the generations before us did (and still do): parents, other family members, peers, religion, education, propaganda, politics, news media and society in general. Add to that the individual conclusions they draw from what happens to them personally, and you get a bunch of very diverse human beings. (Then you have to investigate each one's life personally to get any kind of insight into exactly what they have learned - and why.)
Today's children (what a huge categorisation!) seem in many ways to be very different from the children we were, but they're also different from one another - there has never been a benchmark child against whom every other child can be measured. Don't forget that we were a diverse bunch, too - we didn't (and still don't) agree on what is good, acceptable, moral and ethical.
What's different now is that the world has changed (as it always has done and will continue to do) and worldwide instant media reportage means that each individual's horizons are much wider than they used to be (hello, World Wide Web) so children now have almost all there is to see right in front of their eyes, sometimes even as it's happening (hello, mobile phones with cameras).
I knew when I started this that I wouldn't be able to produce a satisfactory answer. There are so many elements to look at, starting with a bunch of agreed definitions, that this thread stands a good chance of lasting until Trump marries Putin and we all live happily ever after...