The Real Problem: Too Many Promises
Here's where things get messy - Edward the Confessor apparently promised the throne to several different people! This created way more problems than simply not having a son.
William of Normandy claimed Edward promised him the throne around 1051 when the Godwinson family was in exile. Meanwhile, Harold Godwinson insisted Edward named him heir on his deathbed eventhepro−NormanBayeuxTapestryshowsEdwardreachingouttoHarold. Edward also sent bishops to find his nearest blood relative, Edgar the Aetheling, suggesting he might have wanted family to inherit after all.
The three main claimants - William, Harold Godwinson, and Harald Hardrada - were all powerful, wealthy men with strong armies and genuine claims. Hardrada had a claim through an old treaty between previous kings, whilst William even had the Pope's support for his claim.
Though 14-year-old Edgar was probably the rightful heir by blood, the Witan feared he couldn't protect England from Viking and Norman invasions.
Remember: The 1066 crisis happened because Edward made too many promises, not because he lacked a son!