How much time to allow between connecting flight in Frankfurt

I would feel comfortable with that. Tickets booked together, I assume?

Assuming you are either doing carry on only, or your checked bags are tagged through to Geneva- Where is your first flight originating? If it's from another Schengen country, then you should be fine. If from outside Schengen, then you'll have to clear Passport Control and possibly security before your connecting flight. That will be tight. But if you miss your connection, Lufthansa has to get you on the next available flight.

Another factor is that Frankfurt uses a lot of remote gates (i.e., tarmac that has been labeled
a gate. If this happens to your flight, it's another risk factor, as everyone unloads onto a bus,
and the bus doesn't take off until it's full.

Also, if your connecting flight is at a high A numbered gate (A30-40), be prepared for a long
walk.

ms206147, if you can, run. I've had success with that at least a half-dozen times over the years, flying past people on moving sidewalks. Blew them away. Also, running to a connection wakes me up and I feel better, more alert and alive.

If there are 2 or more flights to GVA after yours in case you miss your connection, you’ll be fine assuming it is all on one ticket.

I have been on numerous flights to Frankfurt that have arrived late so I personally would not do that connection of 1.5 hours. My minimum on a connection is 2 hours as I want to reduce the stress of making an international connection as much as I can. So it is up to you and your comfort level and speed with RUNNING with luggage if need be.

I suggest using Flight Aware to research the on-time record of your flight.
Good luck!

We came through Frankfurt on Saturday where we connected to United Airlines' flight to IAD--Washington, D.C. We had two hours to make the flight connection.

United was incredibly unprepared for a full flight, and the long line getting on was going nowhere. We were almost an hour late departing and getting into D.C. Many, many people missed their connecting flights by 15 minutes--including 7 of us. United didn't hold up one flight. The small/medium jets going to our destination were 100% booked for at least the next two days--no flight options. Three of our group stayed with grown children in Washington and got flights Monday or later.

We stayed Saturday night in an IAD airport hotel with food vouchers, and flew early Sunday to Atlanta where we had to rent a car ($400) to get 250 miles to our final destination.

in the future, we will only fly to Europe on airlines that have full size airliners flying out of our medium size city. That means Delta thru Atlanta and American thru DFW. We were not impressed with United's ground operations.

We arrive at 14:50 in Frankfurt

How do you know that you will arrive in Frankfurt at 14:50. From where will you be coming? Do you know your arrival and departure gates?

When I look at the FRA arrival boards, it look like your flight might be coming from Copenhagen. Is that right. In that case you can probably expect a fairly predictable arrival time. From the US, not so much.

If you really arrive at 14:50, and you already know how to get to your departure gate, I think 1H40 is enough time.

To David:
You've posted many times, so I don't mean to imply you aren't aware of this, but
the description of your specific flight sounds like a EC261 delay to me.

David, United messed up do many times on my trips that I finally gave up and started driving to the connection (3.5 hours). It's just not worth the risk of missing the connection on the outbound flight. https://www.youtube.com/watch?v=A732Cuuo2tI