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:
220.127.116.11 The name of the Registered Name;
18.104.22.168 The names of the primary nameserver and secondary nameserver(s) for the Registered Name;
22.214.171.124 The identity of Registrar (which may be provided through Registrar's website);
126.96.36.199 The original creation date of the registration;
188.8.131.52 The expiration date of the registration;
184.108.40.206 The name and postal address of the Registered Name Holder;
220.127.116.11 The name, postal address, e-mail address, voice telephone number, and (where available) fax number of the technical contact for the Registered Name; and
18.104.22.168 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.