Credit File Question

[Madgirl2]

My mum and dad (who have lived in Spain for the last 20 years) hold 3 UK bank accounts. These are simple checking accounts with no overdrafts - just debit cards. If I was to be added to these accounts (thus creating a financial association on my credit file?) Would this affect my credit score? My mum tells me that none of her accounts have ever been in default. Buy I am very conscious that my parents will have lost most of their credit history now. Could this impact on me in any way?.