Why did Petunia Dursley accept Harry at the beginning?

[Geoff Bannister]

No: HPFGUIDX 99636

--- In HPforGrownups at yahoogroups.com, "amanitamuscaria1" 
<saraandra at s...> wrote:

AmanitaMuscaria again - I presume, again, that Harry is vulnerable. 
> The Dementors (if they were Dementors), though not sent by 
Voldemort, 
> as far as we know, didn't attack the house. But why else have a 
watch 
> on Harry when he steps outside the house?
> Cheers. 

Geoff:
I nearly posted this myself. However, I wonder if there is a 
difference between the "Petunia link", which protects Harry from 
Voldemort and other folk from the Wizarding World?