The major family history websites make claims of how easy it is to research your ancestry. Whilst it is true that you can `just type in a name’, often what you then get is heavily based on what other members have researched in the past. The quality of this varies from very good, to complete fiction; the issue is how do you know if it is reliable or not?
As a professional genealogist, I often get asked to start with work that clients have done on one of these websites, and so I have a lot of experience with looking at members’ trees and then obtaining proper proof to see that it is correct. I have to say the majority of these trees have major errors in them. By that, I mean that they contain a mistake and are following the wrong family, at least on some branches.
I have had clients say to me that a lot of other people have the same information, and often this is the case. However, sometimes the more people that have copied the information, the less reliable it actually is. I think it is because those that copy a lot tend not to be as careful with the research and so the errors get propagated in a similar way that fake-news spreads. On many occasions, I have had a situation where perhaps 20 members have concluded one thing but 2 members have concluded something else, and it is very often the minority that are correct!
By all means, use other members online trees as a resource, but be very wary of the information that they contain; Do not assume that they are correct, even if a lot of people have the same information, and always verify the details yourself. And please do not perpetuate the misinformation if you aren’t sure, then mark the fact as questionable in your tree. Avoiding the next sins will help you make sure your research is accurate.