Visitor visa to the UK

Your nationality does not exempt you from the UK visitor visa requirement. To visit the UK without a visa based on your German residence, the following things must be true:

• You have a German residence card issued because you live in Germany with a family member who is an EU citizen or a national of an EEA country or Switzerland.
• The German residence card explicitly states that it was issued for that reason.
• You are traveling to the UK with your family member, or joining your family member in the UK.

The third condition is met, since the question is based on the premise that you are traveling with EEA family members to the UK, but you haven't said whether the first and second conditions are met. If your residence in Germany is based on a family relationship to a German citizen, then the card will normally not say so, because it will have been issued under German domestic law rather than EU free movement law. Similarly, if you acquired German residence independently and then married a Swiss citizen or a national of an EEA state other than Germany, you would only meet this condition if you had changed the legal basis of your residence.

In a comment, user Henning Makholm points out that the definition of family member is also somewhat limited for this purpose. If you have the card mentioned above, you don't much to worry about this. If you do not have that card, however, you need a visa, and the definition of family member will have a bearing on whether you need a standard visitor visa or are eligible for an EEA family permit, which is free of charge.

To get an EEA family permit, you must be traveling with an EEA or Swiss national who meets the criteria under the law. Because of the rule that family of a country's own citizens are subject to national law, If the person you're traveling to the UK with is a citizen of the UK, you would not normally qualify for an EEA family permit. There is an exception to this under certain circumstances if you live with the UK citizen in Germany, though the UK imposes several limitations on that exception.

From the previous link, the criteria are:

Qualifying as a ‘close’ family member

You must be the EEA citizen’s spouse or civil partner, or related to them (or to their spouse or civil partner) as their:

• child or grandchild under 21 years old, or dependent child or grandchild of any age
• dependent parent or grandparent

Family members who are adopted under an adoption order that is recognised in UK law are regarded the same as natural family. Read the guidance on adoption and settlement.

Qualifying as an ‘extended’ family member or unmarried partner

You can apply as an ‘extended’ family member’, for example a brother, sister, aunt, uncle, cousin, nephew or niece.

You must be able to show that you’re dependent on the EEA citizen or are a member of their household, or have a serious health condition and rely on them to care for you.

You can also apply as an unmarried partner if you can show that you’re in a lasting relationship with the EEA national.

Extended family members and unmarried partners are not guaranteed to get a permit. Your individual circumstances will be considered when you apply.