It sounds like your details are in your website's WHOIS records. You can check what is in them here. The data stored include your name, address, e-mail, and often much more.
According to ICANN's specifications:
Until otherwise specified by a Consensus Policy, such data shall consist of the following elements as contained in Registrar's database:
126.96.36.199 The name of the Registered Name;
188.8.131.52 The names of the primary nameserver and secondary nameserver(s) for the Registered Name;
184.108.40.206 The identity of Registrar (which may be provided through Registrar's website);
220.127.116.11 The original creation date of the registration;
18.104.22.168 The expiration date of the registration;
22.214.171.124 The name and postal address of the Registered Name Holder;
126.96.36.199 The name, postal address, e-mail address, voice telephone number, and (where available) fax number of the technical contact for the Registered Name; and
188.8.131.52 The name, postal address, e-mail address, voice telephone number, and (where available) fax number of the administrative contact for the Registered Name.
There are ways of hiding this information. Some registrars have whois privacy which will replace your details with those of a company.