The whole idea that you have to be "fully Italian"/"100% Italian", or have an Italian last name or have an Italian heritage on your father's side in order to be made or join is a myth that people who know nothing love to spread around. The myth of this is perpetuated by myths, and movies and TV shows about the mob that are not based on reality at all.
When mafia members from Sicily, Calabria, and other parts of Italy first immigrated here to the states over a century ago yes you did have to be completely Italian. But it was not that difficult to tell who was Italian and who was not, and there were very few if any first generation Italian-Americans then since they were very young or just being born.
However the whole "you must be completely 100% Italian" in order to join the mob or be made has not applied for over a century, and the idea it does is a myth perpetuated by the media and people who are in the mob who believe the BS history they hear that's not accurate. Even in NYC with the five families you do not have to be completely Italian to join, and it has been this way since the 60s. They never have actually "changed it back". People who claim that they have or that you must be 100% Italian to join believe misinformation and myths about the mob that are not true that get spread around. The stuff the rats and fed reports claim is not necessarily true either.
If they restricted membership to people who were only completely Italian that is Italian on both their father and mother's sides going back to their great-grandparents, or even further back nobody in the United States would be able to join, and not everyone in Italy now would be able to join either.
You do have to have an Italian heritage but it can be on either your mother or father's side. Yes someone who is 1/4th or 1/8th Italian, or even 1/2 Italian can join as long as they are completely Caucasian, and look Italian.
Yes some people do try to get their son, grandson, or great-grandson to join. It's like this in Italy too. They do this despite how their sons or other male relatives are not completely Italian and if the son or other male relative wants to join they easily can despite being 1/2, 1/4, or 1/8 Italian. But if the son is biracial or mixed race such as being Italian, and Asian, Italian and Hispanic, or Italian and Black they do not do this as there's no point and their relative will not be accepted into the business no matter how much they earn or who they are related to.
They would never let someone who is fully, half, or part Asian/Indian, or black, and part Caucasian Italian join or be made. Like that actor Giancarlo Esposito on breaking bad who played the Chilean drug dealer he's Italian and black; but looks black or mixed race. There are also a lot of illegal immigrants from various African countries in Italy now, and some become citizens and marry Italian people and they are not allowed in. The same goes for children or grandchildren of people from various Asian and even European countries who emigrate to Italy, marry an Italian woman or man and do not have a heritage that is actually Italian.
While you make a good point about the difficulty of discerning full or 100% Italian blood today, far removed from pure Italian stock as many prospective members would be today, the idea (which was in fact re-made the rule when Joe Massino was boss of the Bonannos in the early 2000's), it basically meant to the mobsters who were making the rules that both the guy's father and mother had to be Italian. In their way of looking at things - that meant the guy was 100% Italian, whereas a guy could be potentially made prior to that (at least during the 1980's and 1990's) by being what they would consider only 50% Italian on the father's side. How strictly that is actually followed is another story. I tend to agree that as long as a guy is white, has an Italian heritage (including an Italian last name), and the powers that be want him in; he'll get in.
