It's an old (2016) article, but it's an interesting one, and one with which many chess parents will identify. The 40-year-old author and his 4-year-old daughter learned chess together, and to the surprise of no one reading this blog, the daughter was soon crushing dear old dad left and right.
What does this show? Not very much, in itself. It's anecdotal, and we don't know how much time each person spent on the game. But let's assume that it confirms what we probably all believe, which is that kids will pick up the game more quickly than adults in or near middle-age. Even so, I wonder what would happen if the adult first worked on his board vision and fundamental tactical skills, and only then bothered with Larsen's Best Games. (Though I would say that I can scarcely imagine a worse book for a near-beginner to bother with. It's not only nuts because he's a top-level player and the games are going to be far more complicated than a beginner has any business trying to deal with, but also because he had a somewhat eccentric style as well. Bobby Fischer was of course a much better player than Larsen, but his My 60 Memorable Games is far more useful to amateurs because of his clear and direct style and some of the 19th century like wins therein. There are also games in the book which will also be impenetrable to novices, so it makes more sense for newer players to dig into, say, a book of Morphy's best games. Almost all of his opponents play hideously bad chess, and that's what makes the book worthwhile: clear mistakes receive brutal punishment of a sort that you and I can learn to emulate with a fair degree of success.)
Two final remarks. First, to say that it's hard for a 40-year-old to learn from scratch says nothing about a 40-year-old who's already playing. Once one has developed one's board vision and fundamental tactical abilities, they are there. Second, if one is taking up the game at 40 to become the world champion, you're out of luck, but that's no reason not to take the game up for fun and as a mental challenge. So articles like this are unfortunate, to the degree that they discourage adults from learning to play. Ok, kids are going to pick up the game faster than you are. So what? Keep at it, and before you know it no four-year-old is going to catch you without doing a LOT of work over a period of years. If you enjoy the game, play it; if not, then don't, regardless of your relative level of talent. Simple!