In short, it's not real. Nebula actually mentioned this picture in a post a while ago:
NebulaHaze commented
"Unfortunately there's no way to know for sure what the gender is just from looking at the seeds. There's a
graphic that's been floating around since the 2000s that claims it shows you how to do it but it's been basically debunked. I also find it telling that in nearly 10 years I've only ever see this one graphic and never a real grower showing how to do it with real seeds in pictures or video.
From the growers I know who've tried using following the graphic, some say it doesn't work at all, and some say it's not perfect but works more than half the time. I guess that is better than random, but not good enough to bet your grow on. The other problem is sometimes you'll get regular seeds and none of them will "look" female, even though you know half of them are.
If you use the seed identification method on regular seeds you'll always grow a bunch of boys and unintentionally throw away some girls. Thats why breeders and commercial growers never use it and stick with feminized seeds or clones when they're growing for bud instead of breeding.
In fact, even the temperature and humidity during the first few weeks of life can change the ratio of males and females from a regular batch of seeds! So gender doesn't even seem to be set from birth anyway! If it's cool and humid during the first 3 weeks you'll get more female plants, and if it's hot and dry (or plants get stressed), you'll end up with more male plants."