Why does Ned Stark say Jon Snow is his son?

Related questions

1. Why did littlefinger have Jon Arryn killed?
2. Who married rhaegar and Lyanna?
3. How many sons did rhaegar have?
4. Do the Dragons know Jon Snow is a Targaryen?
5. Were Lyanna Stark and rhaegar married?
6. Is Jon Snow Eddard Stark's son?
7. Why did the mad king kill Ned's father?

Tags

1. #believed
2. #death
3. #robert
4. #following
5. #rather
6. #identity
7. #child
8. #targaryen
9. #conceal
10. #baratheon
11. #stark
12. #illegitimate
13. #sister
14. #lyanna
15. #would
16. #rhaegar
17. #trueborn
18. #found